To be able to call himself an associate professor at the newly founded Reichsuniversität Straßburg, he was habilitated in 1941 with the treatise on the subject "Experimentelle Visionen.

After his detention in a British camp between November 1944 and July 1945, he returned to Freiburg im Breisgau, where he was got a lectureship for psychology.

Bender had been skilled in depth psychology and oriented himself mostly by approaches of Pierre Janet and Carl Gustav Jung.

In parapsychology this means that paranormal phenomena were not treated as influences of spirits, but as a result of the great strain of the "focus person".

A term coined by Bender is the so-called uniformity of the occult (in German, Gleichförmigkeit des Okkulten), i.e. the fact that phenomena such as telepathy, clairvoyance, precognition, haunting and psychokinesis are reported from antiquity to the present in all epochs and in the most diverse cultures and regions of the earth, while age, educational level and social status of the experiencers do not seem to play a role.

As an example, he explained in 1982 the haunting case "Chopper" that was proven to be a manipulation of a dental nurse in Neutraubling near to Regensburg headily as authentic to the magazine Die Aktuelle.

In 1978, for example, the detective director Herbert Schäfer of the State Criminal Police Office in Bremen obtained a confession from Heinrich Scholz, the focus person in a haunting case of 1965, which Bender had declared to be genuine.

This case was not only documented by Bender and his assistants, but by technicians of the Post Office and the power plant, by the police and physicists of the Max Planck Institute in Munich.

Notwithstanding the fact that the physicists wrote in their expert opinion that not all the phenomena observed could be explained with the laws of physics, at least in one case, a manipulation of the focus person, a clerk, could be detected.

[3] Skeptical investigator Joe Nickell described Bender as a paranormal believer unwilling "to draw the obvious conclusion from the evidence."

Nickell noted that Bender considered a poltergeist case to have genuine effects even though the subject was discovered to have cheated.

[4] According to magician and paranormal investigator James Randi, due to "his unquestioning acceptance of psi, Bender came in for a great deal of criticism from his colleagues in science, who referred to him as der Spukprofessor ("spook professor")".